The association between physical activity and depressive symptoms in young women : a review

Objective : This review synthesises results of studies examining the association between physical activity (PA) and depressive symptoms and the effects of PA intervention studies on depression among young women.
Methods : A search of electronic databases and bibliographic searches of observational and intervention studies was conducted that included women between the ages of 18 and 35.
Results : A total of eight observational and five intervention studies were identified. Evidence from observational studies indicated that physical activity was inversely associated with depressive symptoms in young women. Even a small amount of physical activity was found to be associated with reduced depressive symptoms. No clear dose–response relationship was shown. Evidence from intervention studies indicated that physical activity reduced depressive symptoms. Direct study comparisons were difficult due to variations in study methods and measures. The studies provided little or no information on understanding dose–response effects or on the mechanisms involved.
Conclusion : The limited number of studies examining physical activity and depressive symptoms in young women and the methodological problems identified in a number of these studies, make it difficult to draw firm conclusions. However, this review suggests that engaging in even low levels of physical activity may be protective against depressive symptoms in young women. There is a need for objective measures of physical activity in future studies, particularly with a focus on those with clinical depression in non-student populations.

Nicotine dependence in a prospective population-based study of adolescents : the protective role of a functional tyrosine hydroxylase polymorphism

Dopamine is a key neurotransmitter of the mesolimbic reward pathway in the human brain, and tyrosine hydroxylase (TH) is the rate-limiting enzyme in dopamine biosynthesis. Consequently, the gene encoding TH is a strong candidate for involvement in the genetic component of addiction. The importance of this gene in nicotine dependence is supported by many studies showing a link between nicotine administration and TH expression. A functional tetranucleotide repeat polymorphism within intron 1 of the TH gene (HUMTH01-VNTR) has been shown to modify tobacco use in two independent Caucasian samples from the USA and Australia. Using information drawn from an eight-wave Australian population-based longitudinal study of adolescent health, we tested the effect of the HUMTH01-VNTR on nicotine dependence. Comparisons were made between dependent smokers and non-dependent smokers. These data provide further support for a protective association between the K4 allele and dependent smoking (odds ratio 0.54, 95% confidence interval 0.28-1.0). No associations were observed at any of three other common TH polymorphisms (rs6356, rs6357 and HUMTH01-PstI). Including these data, three independent studies, two of which use identical phenotypes, have now identified a protective relationship between the K4 allele of the functional HUMTH01-VNTR polymorphism and high-level smoking.

Association between dependent smoking and a polymorphism in the tyrosine hydroxylase gene in a prospective population-based study of adolescent health

This study reports pilot data on an association between tobacco dependence and a five-allele tetranucleotide repeat polymorphism in the first intron of the tyrosine hydroxylase (TH) gene. One hundred and twenty-six Australian adolescents who had participated in the Health in Transition Study (1993–1997), and who showed patterns of either dependent or nondependent smoking across four waves of data collection, consented to participation in the pilot study. The smoking status of those recruited was confirmed using a telephone-administered drug use questionnaire during 2000. Tobacco dependence was defined as smoking more than 6 days per week and more than 10 cigarettes per day during wave 5 (year 2000) and at lfeast one prior wave (n = 58). A second, more stringent phenotype included smoking within an hour of waking (n = 37). The control group comprised adolescents who had used tobacco but had remained low-level social smokers across each wave of data (n = 56). DNA was collected using a mouthwash procedure. Using the more strictly defined tobacco dependence phenotype, and after adjusting for sex, a significant protective association was found between the K4 allele and tobacco dependence (OR 0.27, 95% confidence interval [CI] 0.09, 0.82). No association was found using the liberal criteria of tobacco dependence (OR 0.51, 95% confidence interval [CI] 0.23, 1.2). These preliminary results replicate a previous association between tobacco use and the K4 allele of the TH gene (Lerman et al., 1997). The potential significance of including time to first cigarette in definitions of tobacco dependence and the possible role that these TH variants might play in tobacco dependence are discussed.

The association between mindfulness and emotional distress in adults with diabetes: could mindfulness serve as a buffer? Results from Diabetes MILES: the Netherlands

People with diabetes have a higher risk of emotional distress (anxiety, depression) than non-diabetic or healthy controls. Therefore, identification of factors that can decrease emotional distress is relevant. The aim of the present study was to examine (1) the association between facets of mindfulness and emotional distress; and (2) whether mindfulness might moderate the association between potential adverse conditions (stressful life events and comorbidity) and emotional distress. Analyses were conducted using cross-sectional data (Management and Impact for Long-term Empowerment and Success-Netherlands): 666 participants with diabetes (type 1 or type 2) completed measures of mindfulness (Five Facet Mindfulness Questionnaire-Short Form; FFMQ-SF), depressive symptoms (Patient Health Questionnaire; PHQ-9), and anxiety symptoms (General Anxiety Disorder assessment; GAD-7). Hierarchical multiple regression analyses showed significant associations between mindfulness facets (acting with awareness, non-judging, and non-reacting) and symptoms of anxiety and depression (β = -0.20 to -0.33, all p < 0.001). These mindfulness facets appeared to have a moderating effect on the association between stressful life events and depression and anxiety (all p < 0.01). However, the association between co-morbidity and emotional distress was largely not moderated by mindfulness. In conclusion, mindfulness is negatively related to both depression and anxiety symptoms in people with diabetes and shows promise as a potentially protective characteristic against the influence of stressful events on emotional well-being. © 2014 Springer Science+Business Media New York.

Association between apolipoprotein E polymorphisms and age-related macular degeneration: a HuGE review and meta-analysis

A possible association between apolipoprotein E polymorphisms and age-related macular degeneration has been investigated numerous times, with conflicting results. A previous analysis pooling results from four studies (Schmidt et al., Ophthalmic Genet 2002;23:209-23) suggested an association, but those investigators did not document allele frequencies, the magnitude of the association, or the possible genetic mode of action. Thus, the authors searched MEDLINE from 1966 to December 2005 for any English-language studies reporting genetic associations. Data and study quality were assessed in duplicate. Pooling was performed while checking for heterogeneity and publication bias. Frequencies of the E2 and E4 alleles in Caucasians were approximately 8% and 15%, respectively. Allele- and genotype-based tests of association indicated a risk effect of up to 20% for E2 and a protective effect of up to 40% for E4. E2 appeared to act in a recessive mode and E4 in a dominant mode. There appears to be a differential effect of the E2 and E4 alleles on the risk of age-related macular degeneration, although the possibility of survivor bias needs to be ruled out more definitively.